Development of Colletotrichum acutatum on Tolerant and Susceptible Olea europaea L. cultivars: A Microscopic Analysis

Abstract

Colletotrichum acutatum is a cosmopolitan and damaging plant pathogen of temperate, subtropical, and tropical fruits and causes anthracnose on olive (Olea europaea L.). Three olive cultivars showing a variable response to infection by C. acutatum were selected to a preliminary study of pathogen development. Fruit samples, from susceptible and tolerant cultivars, were taken at 0, 24, 48, 72, and 192 h after inoculation for a microscopic and histological study of the infection and colonization process. The aim of this study was to compare the infection process: conidial germination, germ tube and appressorium formation, hyphal growth, and mesocarp colonization in susceptible and tolerant olive cultivars as a condition for further exploration of disease development, which is required to develop cultivars with improved resistance to anthracnose. The rate of mesocarp colonization differed between the susceptible and tolerant cultivars, and both intracellular hemibiotrophy and subcuticular intramural necrotrophy were observed. Hemibiotrophic infection predominated in the moderately tolerant cultivar.

Infection Process of Olive Fruits by Colletotrichum acutatum and the Protective Role of the Cuticle and Epidermis

“…In previous work the expression of resistance, on olive cultivars, occurred only after pathogen penetrated the physical barriers (Gomes et al, 2008). However, once penetrated, the infection development in 'Picual' (resistant) occurred very slowly, suggesting that fungus can remain in a latent period waiting for favourable environmental conditions.…”

La Antracnosis del olivo y su efecto en la calidad del aceite

“…se expresa como: retraso en la colonización de los tejidos de la aceituna (Gomes et al, 2009), incremento del periodo de latencia, disminución de la tasa máxima de desarrollo de síntomas (Moral et al, 2008) y reducción de la cantidad de inóculo que produce el patógeno (Moral y Trapero, 2012). En campo, se observa una disminución de la tasa máxima de desarrollo de síntomas y un incremento del periodo de latencia, siendo frecuente que las infecciones queden asintomáticas durante periodos prolongados en los cultivares resistentes (Moral y Trapero, 2012;Figura 3).…”

Olive – Colletotrichum acutatum: An Example of Fruit-Fungal Interaction

“…Pathogens may force their way through plant surfaces by different means; some take advantage of natural doors, such as stomata or lenticels; some others enter through wounds or directly through cuticle (Bailey et al, 1992;Gomes et al, 2009;Jong & Ackerveken, 2009). In order to infect plants, fungal pathogens have developed a wide variety of infection strategies: (i) Necrotrophs, pathogen kill the host and feed from the cell contents; (ii) Biotrophs, require a living host to complete their life cycle; and (iii) Hemibiotrophs, act as both biotrophs and necrotrophs at different stages of infection.…”

“…In order to infect plants, fungal pathogens have developed a wide variety of infection strategies: (i) Necrotrophs, pathogen kill the host and feed from the cell contents; (ii) Biotrophs, require a living host to complete their life cycle; and (iii) Hemibiotrophs, act as both biotrophs and necrotrophs at different stages of infection. Most of the Colletotrichum species are hemibiotrophs with different spans of their biotrophic phase, and may also undergo a period of quiescence in order to overcome resistance mechanisms (Gomes et al, 2009;Peres et al, 2005). Two types of interaction between Colletotrichum species and their hosts have been reported: intercellular hemibiotrophy and subcuticular intramural necrotrophy (Gomes et al, 2009;O'Connell et al, 2000;Perfect et al, 1999) (Fig.…”

“…Most of the Colletotrichum species are hemibiotrophs with different spans of their biotrophic phase, and may also undergo a period of quiescence in order to overcome resistance mechanisms (Gomes et al, 2009;Peres et al, 2005). Two types of interaction between Colletotrichum species and their hosts have been reported: intercellular hemibiotrophy and subcuticular intramural necrotrophy (Gomes et al, 2009;O'Connell et al, 2000;Perfect et al, 1999) (Fig. 4).…”